Instrument, system, and method for locating a leakage source

ABSTRACT

An instrument system for locating leakage at a subscriber&#39;s premises is disclosed.

This application is a continuation of U.S. application Ser. No.16/921,870, filed on Jul. 6, 2020, which is a continuation of U.S.application Ser. No. 16/183,487, filed Nov. 7, 2018, which claimspriority under 35 U.S.C. § 119 to U.S. Provisional Patent ApplicationSer. No. 62/583,247, filed on Nov. 8, 2017, and U.S. Provisional PatentApplication Ser. No. 62/660,645, filed on Apr. 20, 2018. Each of thoseapplications is expressly incorporated herein by reference.

TECHNICAL FIELD

The present disclosure relates generally to data-over-cable or cablenetwork system testing, and, more particularly, to instruments andmethods for detecting leakage from a cable network system.

BACKGROUND

Most cable network systems are coaxial-based broadband access systemsthat may take the form of all-coax network systems, hybrid fiber coax(HFC) network systems, or RF over glass (RFOG) network systems. Cablenetwork system designs typically use a tree-and-branch architecture thatpermits bidirectional data transmission, including Internet Protocol(IP) traffic between the cable system head-end and customer locations.There is a forward or downstream signal path (from the cable systemhead-end to the customer location) and a return or upstream signal path(from the customer location back to the cable system head-end). Theupstream and the downstream signals occupy separate frequency bands. Inthe United States, the frequency range of the upstream band is from 5MHz to 42 MHz, 5 MHz to 65 MHz, 5 MHz to 85 MHz, or 5 MHz to 204 MHz,while the downstream frequency band is positioned in a range above theupstream frequency band.

Customer locations may include, for example, cable network system (e.g.,CATV) subscriber's premises. Typical signals coming from a CATVinstallation at the subscriber's premises include, for example, set topbox DVR/On Demand requests, test equipment data channels, and InternetProtocol output cable modem carriers defined by the Data Over CableService Interface Specification (“DOCSIS”), which is one communicationstandard for bidirectional data transport over a cable network system.

Egress or leakage from the cable network system results from flaws inthe cable network system that provide points of ingress for noise, whichcan reduce the quality of service of the system. Service operators haveutilized two basic types of leakage detection gear to locate such pointsof ingress. One type of gear utilizes a signal level meter with anantenna designed to receive signals in the cable network system band. Amaintenance/service technician walks around a subscriber's premisesmonitoring the signal level meter to identify flaws in the wiring andnetwork devices at the subscriber's premises.

The other type of gear is so-called “truck-mounted” units, which aremounted in vehicles that are driven along the data lines and nodes ofthe cable network system, generally by maintenance/service technicians,to monitor leakage along the cable network system.

and associated instrumentation for locating leakage is shown anddescribed in U.S. Patent App. Pub. No. 2017/0251207, which is expresslyincorporated herein by reference.

SUMMARY

According to one aspect of the disclosure, an instrument system forlocating leakage at a subscriber's premises is disclosed. The instrumentsystem includes a transmitter operable to generate signals in a numberof different frequency sub-bands across a frequency range of about 100MHz to about 1.2 GHz and an antenna assembly operable to receive thesignals. The antenna assembly may be coupled to a signal level meter orother test instrument to scan the frequency sub-bands, locate thesignals, and determine the leakage amplitude and frequency.

According to another aspect, the instrument system includes an antennaassembly operable to receive signals in multiple frequency sub-bands andsupply those signals to a signal level meter or other test instrument toscan the frequency sub-bands, locate the signals, and determine theleakage amplitude and frequency.

BRIEF DESCRIPTION OF THE DRAWINGS

The detailed description particularly refers to the following figures,in which:

FIG. 1 is a block diagram illustrating a cable network system, asubscriber's premises, and an instrument system;

FIG. 2 is a block diagram schematic of a transmitter assembly of theinstrument system of FIG. 1;

FIG. 3 is a block diagram schematic of one embodiment of an antennaassembly of the instrument system of FIG. 1;

FIG. 4 is an illustration of the antenna assembly of FIG. 3;

FIG. 5 is a block diagram schematic of a signal level meter of theinstrument system of FIG. 1;

FIG. 6 is a procedure for locating leakage in the subscriber's premisesusing the instrument system of FIG. 1;

FIG. 7 is an illustration of another embodiment of an antenna assemblyof the instrument system of FIG. 1; and

FIG. 8 is a block diagram schematic of the antenna assembly of FIG. 7.

DETAILED DESCRIPTION OF THE DRAWINGS

While the concepts of the present disclosure are susceptible to variousmodifications and alternative forms, specific exemplary embodimentsthereof have been shown by way of example in the drawings and willherein be described in detail. It should be understood, however, thatthere is no intent to limit the concepts of the present disclosure tothe particular forms disclosed, but on the contrary, the intention is tocover all modifications, equivalents, and alternatives falling withinthe spirit and scope of the invention as defined by the appended claims.

Referring now to FIG. 1, an instrument system 10 for use in locatingleakage in a CATV installation 12 at a subscriber's premises 14 isshown. In the illustrative embodiment, the cable network system 20 maybe connected to a subscriber's premises 14 via a data line or cable 22to provide signals including programming material to the subscriber. Thecable network system 20 includes a head end (not shown) whereprogramming material is obtained and modulated onto appropriate carriersfor distribution to a number of subscriber's premises 14. Subscribers'premises may include offices, homes, apartments, or other spaces atwhich CATV content is desired. The carriers may be combined fordistribution downstream to subscribers over what is typically referredto as the forward path. Signals going upstream from subscribers'premises are typically routed in what is called the return path.

The cable 22 may be connected to the subscriber's premises 14 at aground block 24. In the illustrative embodiment, the cable 22 is acoaxial cable. In other embodiment, the cable may include coaxial cableand/or optical fiber that transport the CATV signals. In someembodiments, the CATV signals are transported as radio frequencies (RF).The signals may also be transported in hybrid systems including opticaltransmission portions in which the RF signals are converted to light forfiber optic transmission over some portions of the signal path and as RFsignals over other portions of the signal path.

The ground block 24 is illustratively coupled to the side of thesubscriber's premises 14 and includes a connector 26 configured to becouple to the cable 22. From the ground block 24, a cable 28 enters thehouse and connects to the CATV installation 12. The CATV installation 12defines a “tree and branch” topology with the different branches 30connecting various outlets 32 to the ground block 24.

The instrument system 10 for use in locating leakage in the CATVinstallation 12 includes a transmitter assembly 40, an antenna assembly42 configured to receive signals generated by the transmitter assembly40, and a signal level meter 44 configured to be coupled to the antennaassembly 42. As shown in FIG. 1, the transmitter assembly includes aconnector 46 that is configured to be coupled to the connector 26 of theground block 24 when the cable 22 is disconnected. In the illustrativeembodiment, the connectors 26, 46 are F-connectors and may be male orfemale connectors. As described in greater detail below, the transmitterassembly 40 is operable to generate signals in a number of frequencysub-bands over a frequency range of about 100 MHz to about 1.2 GHz, andthe antenna assembly 42 includes circuitry tuned to each frequencysub-band to receive signals generated by the transmitter assembly 40over the frequency range.

Referring now to FIG. 2, the transmitter assembly 40 includes a numberof electrical circuits 52 to generate signals that are transmitted viathe connector 46. In the illustrative embodiment, the electricalcircuits 52 of the transmitter assembly 40 include a comb generator 54to produce output signals at multiple harmonics. In the illustrativeembodiment, the harmonics output by the comb generator 54 includessignals at multiples of about 138 MHz (i.e., 138 MHz, 276 MHz, 414 MHz,552 MHz . . . ) over a frequency range of about 138 MHz to about 1.2GHz.

As used herein, the term “about” refers to fifteen percent tolerancebased on manufacturing variation and other design criteria. As such, thephrase “about 138 MHz,” for example, encompasses 117.2 MHz, while thephrase “about 1.2 GHz” includes 1380 MHz. It should be appreciated thatin other embodiments signals may be generated at other harmonics, suchas, for example, every 100 MHz over the frequency range.

The output of the comb generator 54 is connected to the input of a tiltcorrection circuit 56 to adjust the signals provided by the combgenerator to make them substantially flat across the frequency range.

The output of the tilt correction circuit 56 is connected to amodulation circuit 58. The modulation circuit 58 is operable to modulatethe output signals from the tilt correction circuit 56 with a tagsignal. In the illustrative embodiment, the tag signal has a frequencyof about 20 Hz at −3 dB. One approach to adding a tag signal is shownand described in U.S. Pat. No. 5,608,428, which is expresslyincorporated herein by reference. It should be appreciated that in otherembodiments the modulation circuit may include a variable modulator topermit the technician to adjust the frequency of the tag signal.

As shown in FIG. 2, the transmitter assembly 40 also includes anamplifier 60 to add gain to the signals output from the modulationcircuit 58. In the illustrative embodiment, the amplifier 60 isconfigured to add gain in a range of about 30 dB to about 40 dB.

The output of the amplifier 60 is connected to the input of a PAD 62.The PAD 62 is configured to be adjusted by the technician to add a highpower offset to the signals output from the amplifier 60. In theillustrative embodiment, PAD is configured to permit the technician toadd between about +40 dBmV to about +60 dBmV or about zero dB to about20 dB. In other embodiments, the PAD is configured to permit thetechnician to add between +40 dBmV to about +80 dBmV or about zero dB toabout 40 dB.

The transmitter assembly 40 includes an outer casing 64 that is shieldedto prevent the circuits 52 from radiating and transmitting signalsthrough the air that might be detected by the antenna assembly 42 andthe signal level meter 44. As shown in FIG. 2, the connector 46 isattached to the outer casing 64 and is configured to output thecomb-generated signals to, for example, the ground block 24 whenconnected to connector 26.

As described above, the connector 46 is configured to be coupled toconnector 26 of the ground block 24 to physically connect thetransmitter assembly 40 with the ground block 24. With the transmitterassembly connected to the ground block, a technician may energize thetransmitter assembly 40 to supply the comb-generated signals to the CATVinstallation 12 at the subscriber's premises 14 via the ground block 24.In the CATV installation 12, there may be some one or more sources ofwhat is known as “flat” (that is, non-frequency dependent, non-distancedependent) loss, for example, (a) splitter(s), (a) tap(s) and so on. Afour-way splitter might have a loss in the range of −7 dB. A tap mighthave a loss in the range of −3 dB. In addition, there is line loss forthe length of coaxial cable between the ground block and a flaw or“leak” in the cable. This loss typically is frequency dependent andmight be, for example, 6 dB/100 ft (about 30.5 m) for about 138 MHz and10 dB/30.5 m for about 750 MHz. If such leakage sources are present inthe CATV installation 12, the comb-generated signals supplied by thetransmitter assembly 40 via the ground block 24 will radiate from thoseleakage sources. As described in greater detail below, the antennaassembly 42 may be used with the signal level meter 44 to detect thesesignals and thereby locate the leakage sources in the CATV installation12.

Referring now to FIG. 3, the antenna assembly 42 includes a connector 66configured to be coupled to a connector 68 of the signal level meter 44.The antenna assembly 42 also includes an antenna 70 configured toreceive signals in a range of about 100 MHz to about 1.2 GHz. Theantenna assembly 42 includes a circuit board assembly 72 that is coupledto the antenna 70 and the connector 66. In the illustrative embodiment,the circuit board assembly 72 includes a number of sub-band circuits 74,76, 78, 80 that correspond to the frequency bands of the comb-generatedsignals provided by the transmitter assembly 40. It should beappreciated that each of the circuits 74, 76, 78, 80 may be a digitaltunable narrow band circuit or passive broad band circuit. A pair ofswitches 82, 84 are operable to selectively connect each of the circuits74, 76, 78, 80 to the connector 66 and the antenna 70 to supply signalsto the signal level meter 44.

As shown in FIG. 3, the frequency range for the circuit 74 is about 100MHz to about 275 MHz and therefore corresponds to the comb-generatedsignals at about 138 MHz. The frequency range for the circuit 76 isabout 275 MHz to about 550 MHz and therefore corresponds to thecomb-generated signals at about 276 MHz and 414 MHz. The frequency rangefor the circuit 78 is about 550 MHz to about 825 MHz and thereforecorresponds to the comb-generated signals at about 552 MHz and 690 MHz.The frequency range for the circuit 80 is about 825 MHz to about 1.2 GHzand therefore corresponds to the comb-generated signal at about 828 MHz,966 MHz, and 1,104 MHz. It should be appreciated that in otherembodiments the transmitter assembly be configured to receive additionalor fewer sub-bands depending on, for example, the overall frequencyrange.

The antenna assembly 42 also includes another connector or port 86configured to receive a control and power cable 88 (see FIG. 1) toconnect the signal level meter 44 to the circuit board assembly 72 andthereby permit the technician to provide power to, and control theoperation of, the switches 82, 84 and the circuits 74, 76, 78, 80.

Referring now to FIG. 4, an exemplary antenna assembly 42 is shown ingreater detail. The antenna assembly 42 covers the frequency range from100 MHz to 1200 MHz with a minimum gain higher than −15 dBi and returnloss better than 8 dB. As shown in FIG. 2, the antenna 70 of the antennaassembly 42 is fabricated on a FR4 PCB (dielectric constant is 4.6) withthe size of 3 in×6 in. The switches 82, 84 are illustratively 1×4switches to connect the circuits 74, 76, 78, 80 and convert antennaimpedance to output a 75 ohm (F connector) impedance. In otherembodiments, 1×4 combiners or multiplexers may be used in place ofswitches or combination of multi-antennas like a patch monopole antennaand a loaded loop antenna, etc. may be used as a wide band antenna, ifthe performance is acceptable based on the system requirements.

As described above, each of the circuits 74, 76, 78, 80 may be a passiveband circuit or a tunable band circuit with lower insertion loss. In theillustrative embodiment, the circuits 78, 80 are passive matchingcircuits, and the circuits 74, 76 are tunable matching circuits. Thecircuit 74 may take the form of a 250 nH inductor in series with acapacitor in a range of about 1.3 pF to about 10 pF. When L=250 nH andcapacitor C changes from 1.3 pF to 10 pF, the matching frequency willmove from about 100 MHz to about 275 MHz, thereby permitting the antennaassembly 42 to receive the comb-generated signal at about 138 MHz. Thevariable capacitor may be a set of PIN diodes with different capacitorvalues, a varactor diode, or digital tunable capacitor (DTC). In someembodiments, the variable capacitor may be a Peregrine DTC PE64102 (forthe 100 MHz to 275 MHz range). The variable capacitor (and hence thecircuit 74) may be controlled by a signal received from the signal levelmeter 44 via the control cable 88.

The circuit 76 may take the form of a 250 nH inductor in series with acapacitor in a range of about 0.9 pF to about 4.6 pF. When L=250 nH andthe capacitor C changes from 0.9 pF to 4.6 pF, the matching frequencywill move from about 275 MHz to about 550 MHz. In some embodiments, thevariable capacitor may be a Peregrine DTC PE64906 (for the 275 MHz to550 MHz range). As described above, the variable capacitor (and hencethe circuit 76) may be controlled by signal received from the signallevel meter 44 via the control cable 88.

It should be appreciated that since the size of the antenna 70 in FIG. 4is much smaller than the wavelength (A) at low frequency (for example, 6in is about A/20 of 100 MHz), the matching circuits 74, 76, 78, 80 playan important role for proper gain over the entire frequency band of theantenna assembly 42.

Referring now to FIG. 5, the signal level meter 44 includes an outercasing 90 that houses various electronic components for analyzing thesignals received via the connector 68 and other connectors, including,for example, the connector 100. In the illustrative embodiment, themeter 44 includes a touchscreen display 102 and various control buttons104 that may be utilized by the technician to operate the meter 44 andanalyze signals received by it. The meter 44 also includes anInput/Output (I/O) port 106 such as, for example, a USB port, that isconfigured to be connected to the control cable 88 to control theoperation of the antenna assembly 42. The meter 44 may also include aspeaker or other device operable to generate audible signals.

The meter 44 also includes an electronic control unit (ECU) or“electronic controller” 110, which is configured to control theoperation of the meter 44. The electronic controller 110 includes aDigital Signal Processor (DSP), but in other embodiments the controller110 may include one or more Field Programmable Gate Arrays (FPGA) andCable Modem Chips. Each of the components described above (e.g., thedisplay 102, connectors 68, 100, control buttons 104, I/O port 106, andso forth) is connected to the electronic controller 110 via a number ofcommunication links such as printed circuit board traces, wires, cables,and the like, which are connected to an interface circuit 116, as shownin FIG. 5.

The electronic controller 110 includes, amongst other componentscustomarily included in such devices, a processor such as amicroprocessor 112 and a memory device 114 such as a programmableread-only memory device (“PROM”) including erasable PROM's (EPROM's orEEPROM's). The memory device 114 is provided to store, amongst otherthings, instructions in the form of, for example, a software routine (orroutines) which, when executed by the microprocessor 112, allows theelectronic controller 110 to control operation of the meter 44 (andhence, for example, the antenna assembly 42). In the illustrativeembodiment, the memory device 114 has stored therein a number ofnormalization tables associated with the range of possible drop levelsof the subscribers' premises 14 and the range of possible transmitlevels of the transmitter assembly 40.

Referring now to FIG. 6, an exemplary procedure 200 for locating aleakage in the CATV installation 12 of a subscriber's premises 14 isshown. The procedure 200 may begin in block 210 in which a technicianmay determine and record a drop level of the CATV installation 12. To doso, the technician may disconnect the cable 22 from the ground block 24.The technician may then connect the signal level meter 44 to the groundblock 24 and operate the signal level meter 44 to record the drop level.

The procedure 200 may then proceed to block 212 in which the technicianmay determine the transmit level of the transmitter assembly 40. To doso, the technician may connect the transmitter assembly 40 the connector100 of the signal level meter 44. The technician may then operate thesignal level meter 44 to determine the transmit level associated withthat particular transmitter assembly 40.

The transmit level and the drop level are stored in the memory device114. Additionally, the technician may separately record in the memorydevice 114 the frequency response of the antenna assembly 42, which maybe determined at the time of manufacture. The signal level meter 44 mayutilize the antenna response, drop level, and transmit level to accessthe normalization tables stored in the memory device 114 and determine acorrection that may be needed to adjust the operation of the signallevel meter 44 to the specific configurations of the subscriber's CATVinstallation, the transmitter assembly, and the antenna assembly.

The procedure 200 may proceed to block 214 in which the techniciandisconnects the transmitter assembly 40 from the signal level meter 44and connects the transmitter assembly 40 to the ground block 24, asdescribed above. With the transmitter assembly 40 attached to the groundblock 24, the technician may energize the transmitter assembly 40 tosupply the comb-generated signals to the CATV installation 12 via theground block 24. The technician may then walk around the subscriber'spremises 14 with the antenna assembly 42 and the signal level meter 44scanning for signals.

To do so, the procedure 200 may advance to block 216 in which thetechnician monitors the display 102 for high energy signals whilewalking around the subscriber's premises 14. In the illustrativeembodiment, high energy signals may be in a range of approximately 0.45mV/m of the corrected signal (i.e., the signal after the offsets,normalizations, and antenna corrections are subtracted out). If thetechnician determines the energy level is in the range (e.g., greaterthan 0.45 mV/m of the corrected signal) in block 218, the procedure 200advances to block 220. If the energy level remains below the range, thetechnician may continue to walk around the subscriber's premises 14scanning for high energy signals in block 216.

In block 220, the technician may operate the signal level meter 44 toapply a filter for the tag signal to the signal received via the antennaassembly 42. If the technician determines, by, for example, monitoringthe display, that the signal level meter 44 has detected the tag signalat 20 Hz in block 222, the procedure may advance to block 224. If thetag signal is not present, the noise source is not related to leakage,and the technician may continue to walk around the subscriber's premises14 scanning for high energy signals in block 216.

In block 224, the technician may operate the signal level meter 44 toselectively couple the circuits 74, 76, 78, 80 to the antenna 70 and theoutput connector 68 of the antenna assembly 42. As the circuits 74, 76,78, 80 are coupled in turn to the antenna 70 and the output connector68, signals in the various frequency sub-bands of the circuits 74, 76,78, 80 are received by the signal level meter 44. In block 226, thetechnician reviews the signals associated with each of the frequencysub-bands, looking for the comb-generated signals associated with eachsub-band and the amplitude of the leakage in each sub-band to identifythe peak leakage signal and its frequency.

After locating the peak leakage signal across the 100 MHz to 1.2 GHzfrequency range, the technician may begin maintenance of the CATVinstallation 12 in block 228, eliminating defects, shielding leakagesources, and taking other actions to reduce the peak leakage to anacceptable level to permit the CATV installation 12 to be connected tothe cable network system 20.

Referring now to FIGS. 7-8, another embodiment of an antenna assembly310 is shown. Like the antenna assembly 42, the antenna assembly 310 isconfigured to receive signals generated by the transmitter assembly 40over the frequency range described above and includes a port 344 (i.e.,F-connector) configured to be coupled to the signal level meter. Asshown in FIG. 7, the antenna assembly 310 includes a monopole antenna312 and a loop antenna 314. In the illustrative embodiment, the monopoleantenna 312 is printed on a dielectric substrate and is configured toreceive signals in a frequency range of 300 MHz to 1,200 MHz with 12 dBof gain tilt. The monopole antenna 312 is generally triangular-shaped inthe illustrative embodiment to receive the wideband signal. In otherembodiments, the antenna may be a metal cylinder or spherical shape toact as a wideband small antenna.

The loop antenna 314 is also printed on a dielectric substrate with aseries inductor shunted with a resistor. As described in greater detailbelow, the loop antenna 314 is configured to introduce a low-Q impedancematch at 150 MHz to extend the frequency range of antenna assembly 310to 150 MHz. In the illustrative embodiment, the antenna assembly 310 hasa minimum gain higher than −15 dBi over the frequency range of 150 MHzto 1,200 MHz and a return loss of better than 5 dB. It should beappreciated that in other embodiments the antenna assembly 310 may alsoinclude a short monopole antenna such as, for example, a rubber duckyantenna or rubber duck aerial to receive signals below 150 MHz.

As shown in FIG. 7, the loop antenna 314 is connected to a resonantcircuit 316 configured to make the loop antenna 314 resonant at 150 MHzwith a low Q. In the illustrative embodiment, Q is less than 10. Theresonant circuit 316 and the monopole antenna 312 are connected to animpedance matching circuit 318 configured to match the signals from thecircuit 316 and the monopole antenna 312 to the external load impedanceof the antenna assembly 310.

Referring now to FIG. 8, exemplary circuits 316, 318 of the antennaassembly 310 are shown in greater detail. In the illustrativeembodiment, the resonant circuit 316 includes a resistor 330 in parallelwith an inductor 332, which are connected to an end 334 of the loopantenna 314. The resistor 330 and the inductor 332 are also connected toanother inductor 336. The resistor 330 is a 150 Ohm resistor, theinductor 332 is a 39 nano-Henry inductor, and the inductor 336 is a 10nano-Henry inductor in the illustrative embodiment.

The resonant circuit 316 also includes a resistor 338 that is connectedto an end 340 of the loop antenna 314 and a capacitor 342 connectedbetween the resistor 338 and the inductor 336. The resistor 338 has is 0Ohm resistor, and the capacitor 342 is a 0.1 micro-farad capacitor. Asdescribed above, the resistor 330, inductor 332, inductor 336, capacitor342, and resistor 338 make the loop antenna 314 resonant at 150 MHz witha low-Q loaded on the monopole antenna 312. It should be appreciatedthat the values of the inductor 336, capacitor 342, and resistor 338 maychange to target a different resonant frequency.

The impedance matching circuit 318 is connected between the resonantcircuit 316 and the output port 344 of the antenna assembly 310. Thecircuit 318 includes an inductor 350 and a pair of capacitors 352, 354.The inductor 350 is a 10 nano-Henry inductor, the capacitor 352 is a 0.3pico-farad capacitor, and the capacitor 354 is a 0.1 pico-faradcapacitor in the illustrative embodiment. As described above, theinductor 350 and capacitors 352, 354 are used for matching to theexternal load impedance of the antenna assembly 310.

While the disclosure has been illustrated and described in detail in thedrawings and foregoing description, such an illustration and descriptionis to be considered as exemplary and not restrictive in character, itbeing understood that only illustrative embodiments have been shown anddescribed and that all changes and modifications that come within thespirit of the disclosure are desired to be protected.

There are a plurality of advantages of the present disclosure arisingfrom the various features of the method, apparatus, and system describedherein. It will be noted that alternative embodiments of the method,apparatus, and system of the present disclosure may not include all ofthe features described yet still benefit from at least some of theadvantages of such features. Those of ordinary skill in the art mayreadily devise their own implementations of the method, apparatus, andsystem that incorporate one or more of the features of the presentinvention and fall within the spirit and scope of the present disclosureas defined by the appended claims.

The invention claimed is:
 1. An antenna assembly for a test instrument,said antenna assembly comprising: an antenna comprising a monopoleantenna and a loop antenna; a plurality of sub-band circuits connectedto the antenna via a first switching circuit, each sub-band circuitbeing configured to receive signals from the antenna in a respectivesub-band of multiple frequency sub-bands and supply the received signalsvia a second switching circuit to a signal level meter or other testinstrument connected to the antenna assembly, the multiple frequencysub-bands comprising a frequency range divided into consecutive sub-bandfrequency ranges; a resonant circuit configured to make the loop antennabeing resonant at about 150 MHz; and an impedance matching circuitconnected to an output of the resonant circuit.
 2. The antenna assemblyof claim 1, wherein the plurality of sub-band circuits are selectivelyconfigured to receive signals in the frequency range of about 100 MHz toabout 1.2 GHz.
 3. The antenna assembly of claim 1, wherein the pluralityof sub-band circuits comprise: a first sub-band circuit adapted toreceive signals in a first sub-band frequency range of about 100 MHz toabout 275 MHz; a second sub-band circuit adapted to receive signals in asecond sub-band frequency range of about 275 MHz to about 550 MHz; athird sub-band circuit adapted to receive signals in a third sub-bandfrequency range of about 550 MHz to about 825 MHz; and a fourth sub-bandcircuit adapted to receive signals in a fourth sub-band frequency rangeof about 825 MHz to about 1.2 GHz.
 4. The antenna assembly of claim 1,wherein the monopole antenna is configured to receive signals in afrequency range of about 300 MHz to 1.2 GHz and the loop antenna isconfigured to extend the frequency range to about 150 MHz.
 5. Aninstrument system comprising: a transmitter device configured to besecured to a port of a cable television network, the transmitter deviceoperable to generate and transmit signals in a number of differentfrequency sub-bands across a frequency range of about 100 MHz to about1.2 GHz; and a test instrument connected to an antenna assembly, theantenna assembly comprising: an antenna; and a plurality of sub-bandcircuits connected to the antenna via a first switching circuit, eachsub-band circuit being configured to receive signals from the antenna ina respective sub-band of the frequency sub-bands and supply the receivedsignals via a second switching circuit to the test instrument connectedto the antenna assembly.
 6. The instrument system of claim 5, whereinthe test instrument is operable to scan the frequency sub-bands anddetermine a leakage amplitude and frequency.
 7. The instrument system ofclaim 5, wherein the transmitter device is further configured tomodulate the generated signals with tag signals.
 8. The instrumentsystem of claim 7, wherein the tag signals have a frequency of about 20Hz.
 9. The instrument system of claim 5, wherein the transmitter devicecomprises a comb generator adapted to produce output signals at multipleharmonics over the frequency range.
 10. The instrument system of claim9, wherein the harmonics output by the comb generator include signals atmultiples of about 138 MHz.
 11. The instrument system of claim 9,wherein the transmitter device further comprises a tilt correctioncircuit adapted to adjust the signals provided by the comb generator tomake them substantially flat across the frequency range.
 12. Theinstrument system of claim 11, wherein the transmitter device furthercomprises a modulator coupled to the output of the tilt correctioncircuit, said modulator configured to modulate signals output from thetilt correction circuit with tag signals.
 13. The instrument system ofclaim 12, wherein the transmitter device further comprises: an amplifiercoupled to an output of the modulator to add gain to the modulatedsignals output from the tilt correction circuit with tag signals; and apad coupled to an output of the amplifier and being adjustable to add ahigh power offset to signals output by the amplifier.